Low- and high-intensity one-week occlusion training improves muscle oxygen consumption and reduces muscle fatigue.

BACKGROUND: Low-intensity resistance exercises with blood flow restriction have been shown is effective to increase muscular strength and hypertrophy. However, the effects of combined training: one-week occlusion training with various exercise intensities by using less occlusion pressure on muscle strength improvement, fatigability and their work capacity are not clear. METHODS: Participants (N.=24) were middle-distance runners with 4-6 years of training experience. A control group without blood flow restriction (N.=12, age 23±1 years) and an experimental group with blood flow restriction (N.=12, age 22±1 years). In this study, the calf muscles were impacted by the training with occlusion 120 mmHg. We used intensive one-week daily training, whereby exercise intensity was gradually increased daily from 20% to 80% of maximal voluntary contraction (MVC) and then decreased to 60% by the end of the week. RESULTS: MVC of foot flexion muscles after the one-week occlusion training in the experimental group and control group increased (P<0.05) by 5.6±1.3% and 5.3±1.2%, respectively. Meanwhile in experimental group work capacity improved only 2.4±3.5% (P>0.05) and in control group it significantly decreased 11.8±2.5% (P<0.05). StO2 decreased during exercise test from the baseline 100% to 45.2±4.3% before occlusion training and to 34.6±6.2% after the week of occlusion training (P<0.05). CONCLUSIONS: Intensive one-week training with occlusion with varying intensity improves resistance to fatigue and recovery after training. This kind of training improves oxygen consumption while exercising.

Blood flow restriction late in recovery after heavy resistance exercise hampers muscle recuperation.

PURPOSE: This study aimed to examine the effect of acute blood flow restriction during the late recovery phase between two resistance exercise bouts on muscular endurance and oxygenation. METHODS: Amateur male middle- and long-distance runners performed two bouts of one-leg dynamic plantar flexion exercise to failure with the load equivalent to 75% of maximum. Subjects were randomly assigned into two experimental groups with thigh occlusion pressure between bouts at either 120 or 200 mmHg with 20 min of passive rest in between, and two control groups without any blood flow restriction separated by either 5 or 20 min of rest. Blood flow restriction in the experimental groups was implemented during the last 15 min of recovery. Calf arterial blood flow and muscle oxygenation were measured by venous occlusion plethysmography and near-infrared spectroscopy, respectively. RESULTS: Decrease of muscular oxygenation and blood flow during recovery between exercise bouts depended on the applied occlusion pressure. When compared with bout 1, work capacity in the experimental groups during bout 2 was reduced by 9.3 ± 2.2% with 120 mmHg and by 10.5 ± 3.1% (p < 0.05) with 200 mmHg occlusion pressure. In the control groups, work capacity was restored after 20 min (- 3.9 ± 3.2%, p > 0.05) but not after 5-min recovery (- 20.0 ± 1.8%, p < 0.05). CONCLUSIONS: Blood flow restriction late in recovery after a heavy resistance exercise bout decreased muscle oxygenation and work capacity during the subsequent heavy resistance exercise bout.

Effects of High Velocity Elastic Band versus Heavy Resistance Training on Hamstring Strength, Activation, and Sprint Running Performance.

Hamstring muscle injuries occur during high-speed activities, which suggests that muscular strength at high velocities may be more important than maximal strength. This study examined hamstring adaptations to training for maximal strength and for strength at high velocities. Physically active men (n = 25; age, 23.0 ± 3.2 years) were randomly divided into: (1) a resistance training (RT, n = 8) group, which performed high-load, low-velocity concentric-eccentric hamstring contractions; (2) a resistance training concentric (RTC; n = 9) group, which performed high-load, low-velocity concentric-only hamstring contractions; and (3) a high-velocity elastic band training (HVT, n = 8) group, which performed low-load, high-velocity concentric-eccentric hamstring contractions. Pre- and posttraining tests included hamstring strength on a hamstring-curl apparatus, concentric knee extension-flexion at 60°/s, 240°/s, and 450°/s, eccentric knee flexion at 60°/s and 240°/s, hamstring and quadriceps coactivation, knee flexion and extension frequency in the prone position, and 30-m sprint running speed from a stationary start and with a running start. Knee flexor torque increased significantly by 21.1% ± 8.1% in the RTC group and 16.2% ± 4.2% in the RT group (p < 0.05 for both groups). Hamstring coactivation decreased significantly in both groups. In the HVT group, knee flexion and extension frequency increased by 17.8% ± 8.2%, concentric peak torque of the knee flexors at 450°/s increased by 31.0% ± 12.0%, hamstring coactivation decreased, and running performance over 30 m improved (p < 0.05 for all parameters). These findings suggest that resistance training at high velocities is superior to traditional heavy resistance training for increasing knee flexor strength at high velocities, movement frequency, and sprint running performance. These findings also indicate that traditional training approaches are effective for increasing knee flexor strength and reducing knee extensor coactivation, but this outcome is limited to low and moderate speeds.

Effect of Electrical Myostimulation on the Function of Lower Leg Muscles.

Electrical myostimulation (EMS) method is applied to improve skeletal muscle function. The aim of this study was to evaluate the efficacy of EMS applied to the sole and calf muscles on their strength and on maximal sprint performance. Each of 10 training sessions involved 10 seconds of stimulation and 50 seconds of rest for a total of 10 minutes. After the 10 training sessions, the maximal voluntary contraction (MVC) of right calf muscles increased by 6.0% from 830.0 ± 47.0 N to 878.0 ± 45.3 N (p ≤ 0.05). When EMS was applied to trained athletes, their 10-m sprint performance improved by 2.1% (p ≤ 0.05). In the second part of the study, a 3-week training program with EMS was applied to athletes, which significantly improved their 10-m sprint performance from a standing start by 5.3% and from a running start by 4.7% (p ≤ 0.05). Thus, 10 EMS cycles up to the maximal tolerated intensity applied every other day improved the MVC of foot flexion muscles and 10-m sprint performance from both standing and running starts. Three weeks of EMS training did not affect the intensity of calf muscle blood flow and oxygen saturation at rest. The training program supplemented with 10 EMS sessions produced significantly greater effects on the 10-m sprint performance from both a standing and a running start.

Interval Running Training Improves Cognitive Flexibility and Aerobic Power of Young Healthy Adults.

Venckunas, T, Snieckus, A, Trinkunas, E, Baranauskiene, N, Solianik, R, Juodsnukis, A, Streckis, V, and Kamandulis, S. Interval running training improves cognitive flexibility and aerobic power of young healthy adults. J Strength Cond Res 30(8): 2114-2121, 2016-The benefits of regular physical exercise may well extend beyond the reduction of chronic diseases risk and augmentation of working capacity, to many other aspects of human well-being, including improved cognitive functioning. Although the effects of moderate intensity continuous training on cognitive performance are relatively well studied, the benefits of interval training have not been investigated in this respect so far. The aim of the current study was to assess whether 7 weeks of interval running training is effective at improving both aerobic fitness and cognitive performance. For this purpose, 8 young dinghy sailors (6 boys and 2 girls) completed the interval running program with 200 m and 2,000 m running performance, cycling maximal oxygen uptake, and cognitive function was measured before and after the intervention. The control group consisted of healthy age-matched subjects (8 boys and 2 girls) who continued their active lifestyle and were tested in the same way as the experimental group, but did not complete any regular training. In the experimental group, 200 m and 2,000 m running performance and cycling maximal oxygen uptake increased together with improved results on cognitive flexibility tasks. No changes in the results of short-term and working memory tasks were observed in the experimental group, and no changes in any of the measured indices were evident in the controls. In conclusion, 7 weeks of interval running training improved running performance and cycling aerobic power, and were sufficient to improve the ability to adjust behavior to changing demands in young active individuals.

Cardiovascular changes during the performance by nonathletes of Bosco repeated jumps anaerobic test.

OBJECTIVE: The aim of this study was to find out the characteristics of cardiovascular changes when performing Bosco repeated jumps anaerobic test depending on the duration of jumping in a nonathletes cohort. MATERIALS AND METHODS: Changes in arterial blood pressure indices and changes in 12-lead ECG indices were analyzed. The characteristics of recovery after workloads were assessed by evaluating the time of half period of recovery of registered indices and by the Lyapunov exponent. RESULTS: The results have shown that the ratio of JT and RR intervals of ECG (JT/RR) can be useful for outlining to what extent a cardiovascular function was mobilized. The mobilization of cardiovascular function when performing a 30-s jump test changed up to 0.454±0.012 and when performing a Bosco test, up to the maximal values, i.e. 0.634±0.004. When performing jumps of maximal intensity, a maximal change of JT/RR occurrence was between 50 and 60s. The increasingly serious myocardial ischemic episodes were observed at the onset of the jumping task. The duration of 60-s of all-out jump test has made an influence on the stability of the recovery processes of cardiovascular indices, i.e. the nonexponential type of recovery was observed. CONCLUSIONS: When performing Bosco 60-s repeated jumps in an anaerobic test, a maximal mobilization of the cardiovascular system occurs between 50 and 60s. The 30-s all-out test duration in jumping is enough to outline at what extent cardiovascular function was mobilized as well as to assess other functional characteristics during high intensity intensive exercising.

Effect of lower body compression garments on hemodynamics in response to running session.

PURPOSE: Compression garments are often worn during exercise and allegedly have ergogenic and/or physiological effects. In this study, we compared hemodynamics and running performance while wearing compression and loose-fit breeches. We hypothesized that in neutral-warm environment compression breeches impair performance by diminishing body cooling via evaporative sweat loss and redistributing blood from active musculature to skin leading to a larger rise in body temperature and prolonging recovery of hemodynamics after exercise. METHODS: Changes in hemodynamics (leg blood flow, heart rate, and blood pressure during orthoclinostatic test), calf muscle tissue oxygenation, and skin and core temperatures were measured in response to 30 min running (simulation of aerobic training session) followed by maximal 400 m sprint (evaluation of running performance) in recreationally active females (25.1 ± 4.2 yrs; 63.0 ± 8.6 kg) wearing compression or loose-fit breeches in randomized fashion. RESULTS: Wearing compression breeches resulted in larger skin temperature rise under the garment during exercise and recovery (by about 1 °C, P < 0.05; statistical power > 85%), while core temperature dynamics and other measured parameters including circulation, running performance, and sensations were similar compared to wearing loose-fit breeches (P > 0.05). CONCLUSION: Compared with loose-fit breeches, compression breeches have neither positive nor negative physiological and performance effects for females running in thermoneutral environment.

Influence of short breathing stop on the cardiovascular system during exercise testing.

Breathing is both a voluntary and an involuntary action, and the changes in breathing intensity or breathing stops has an influence on vegetative functions of the body during exercise. The aim of this study was to determine the possible changes in cardiovascular parameters when patients shortly stopped to breath at the beginning of exercise testing. MATERIAL AND METHODS. Two series of investigation were performed. During the first investigation, the psychomotor tonus was assessed, and the breathing frequency during exercising was monitored in the cohort of 27 healthy adult males who were recruited for the first time to be participants of exercise testing. All the participants performed the Roufier exercise test (30 squats per 45 s). A 12-lead electrocardiogram was continuously recorded during exercise and first two minutes of recovery, and arterial blood pressure was measured at each minute of experiment. During the second investigation, the influence of short breathing stop for 15 s on the changes in cardiovascular functional parameters during exercise test was evaluated. RESULTS. The results obtained during the study showed that patients who had increased psychomotor tonus stopped the breathing involuntary more frequently at the beginning of exercise testing. An involuntary or voluntary breathing stop at the beginning of exercising had an influence on the dynamics of cardiovascular parameters during exercise and recovery: heart rate increased more slowly; lesser changes in the JT interval of electrocardiogram, a trend toward an increase in the arterial blood pressure, and a significantly slower recovery of cardiovascular parameters were documented. CONCLUSION. An involuntary breathing stop caused the changes in cardiovascular parameters during exercise and recovery; therefore, functional status might be assessed not so accurately.